Page:Practical Treatise on Milling and Milling Machines.djvu/83

Rh The index plates furnished divide all numbers to 100, all even numbers to 134, and all numbers divisible by 4 to 200. In addition to cutting gears, this attachment may be used on jig work where accurate indexing is an essential element. The spindle is threaded for the purpose of holding a chuck or face plate.

Vertical Spindle Milling Attachments. Vertical spindle milling attachments, including the Compound and Universal types, are used for a wide range of light and heavy milling, such as key seating, T slot cutting, spiral milling, face milling and work of a similar class; in fact, almost any operation that can be performed with a vertical

spindle machine can be accomplished with a horizontal spindle machine when equipped with one of these attachments.

In die sinking, as well as all kinds of surface milling, the advantage of having the work flat on the table and in plain sight of the operator is readily appreciated. For metal patterns and similar work, these attachments are especially valuable, as a line or template can be followed very closely, thus reducing the hand finishing to a minimum.

It is very essential in designing attachments of this kind, that ample provision be made for solidly clamping the mechanism to the machine, and unless this can be done, their value is greatly restricted. The method of clamping shown in the accompanying illustrations is such that the attachment becomes practically an integral part of the machine. To be practical, the method of clamping must also be simple, for much of the value of an attachment lies in the convenience with which it can be put on and taken off the machine.

In all cases, the spindles of the attachments illustrated can be set to any angle from a vertical to a horizontal position, the angle being indicated by graduations reading to degrees. Attachments of this kind are usually driven from the machine spindle through bevel gears, but Fig. 28 shows one that is driven by